1. Field of the Invention
This invention relates to an improved process for preparing a phosphorus complex and, in particular, phenyltrichlorophosphonium hexachlorophosphate.
2. Related Information
The phosphorus complex of this invention, exemplified by the compound phenyltrichlorophosphonium hexachlorophosphate, is well known in the art and is used in the preparation of various phosphorus-containing compounds.
The article entitled, "Reaction of Phosphorus Pentachloride With Unsaturated Hydrocarbons" by G. K. Fedorova and A. V. Kirsanov, Zhur. Obshchei. Khim. 30 4044 (1960), reported the reaction of styrene with phosphorus pentachloride to form a colorless complex with the structure C.sub.6 H.sub.5 CH.dbd.CHPCl.sub.3.sup.+.PCl.sub.6.sup.-. This reference further disclosed the reaction of arylphosphonous dichloride with phosphorus pentachloride to form a complex of formula ArPCl.sub.3.sup.+.PCl.sub.6.sup.-. These reactions were carried out in benzene at temperatures ranging from about 70.degree. C. to about 80.degree. C. The yield of the complex realized ranged from about 60 weight percent to about 80 weight pecent. However, this reference does not disclose the unique process of this invention, especially because it uses different reagents and does not disclose yields of phosphorus complex in substantially quantitative amounts.
In the article entitled, "Tetrachloro(m-and p-nitrophenyl) Phosphoranes" by I. N. Zhmurova and I. Yu. Voitsekhovskaya, Org. Phos. Comp. Ref. 705, Vol. 3, Monatsh. 70 1-19 (1937), the reaction disclosed in the previous reference was cited for preparing the phosphorus complex. It was further stated therein, that m- and p-nitrophenylphosphonic dichlorides required more severe reaction conditions that in the case of arylphosphonic dichlorides which do not contain a nitro group. In particular, it stated that phenyl- and p-tolyl-phosphonic dichlorides react with phosphorus pentachloride in boiling benzene, but m- and p-nitrophenylphosphonic dichlorides react only when heated with phosphorus pentachloride at 150.degree. C. in absence of solvent. This reference further discloses that when nitrophenylphosphonic dichloride and phosphorus pentachloride were heated with a condenser set for distillation and a receiver cooled to -80.degree. C. for phosphoryl chloride, the yield realized was only about 65 to about 75 weight percent. It is noted, that in the course of the reaction only a small amount of phosphorus oxychloride was distilled off and the reaction was carried out in the absence of a solvent. The improvements disclosed by the present invention are not disclosed by this reference.
U.S. Pat. No. 4,634,771 issued to Shim et al. Jan. 6, 1987, discloses the reaction of carboxylic acid groups on an aromatic ring compound with a phenylphosphonous dichloride, chlorine, and phosphorus trichloride to convert the carboxylic acid groups to trichloromethyl groups. This reference distinguishes the use of phosphorus pentachloride and suggests that it is specific for the conversion of a carboxylic acid group adjacent, or alpha, to the heteroatom of a N-heteroaromatic (N=nitrogen) compound. This patent further distinguishes the use of phenylphosphonic dichloride and phosphorus pentachloride, citing the disadvantage of requiring the handling of solid phosphorus pentachloride which, due to its sensitivity to moisture, requires special handling conditions. This reference, therefore, effectively distinguishes itself from the invention disclosed herein.